Are e-cigarettes a savior for smokers, a lurking global danger … or both?

You might think I’d know. After all, I’m director of the Institute for Global Tobacco Control at the Johns Hopkins Bloomberg School of Public Health. I’ve been involved in tobacco policy research for more than two decades, studying everything from what helps people quit smoking to how tobacco policy is made to how tobacco is packaged. I was recently a voting member on the Food and Drug Administration's Tobacco Products Scientific Advisory Committee.

Yet I can’t — with any degree of certainty — say e-cigarettes are good or bad.

I have esteemed colleagues in the world of public health who will tell you, citing research, that these devices are dangerous. Equally accomplished colleagues will tell you that hundreds of thousands of lives, if not millions, could be saved if tobacco smokers would switch to vaping while turning their backs on cigarettes.

This degree of uncertainty isn’t what makes science weak. It’s what makes science strong. You see, science doesn’t happen with the flip of a switch, but rather arrives incrementally, as if by dimmer. It’s only completely illuminating when we’ve fully turned the knob. And truth be told, we’re never done turning the knob.

I understand that this doesn’t provide sharp guidance or relief in the real world, even as the FDA actively considers whether, or how, to regulate this product. Both young people and adults are using e-cigarettes, which have become a booming business in just a few years. The impact of these devices — whether good or bad — swells with each passing minute.

Though new research on e-cigarettes is now arriving with regularity, much of it is contradictory or provides only tiny pieces of an enormous public health puzzle. For instance, an exhaustive expert review of available data recently completed in the United Kingdom concluded that e-cigarettes are much less harmful than traditional tobacco cigarettes.

Yet in the United States, the FDA has voiced concern that e-cigarettes can hook young people on nicotine and might include ingredients “known to be toxic to humans.” Carcinogens and other toxic chemicals have been found in nicotine liquids and in e-cigarette aerosols. Nicotine liquids include flavors that are alluring to youth — such as banana split, grape, and bubble gum — and the advertising for these products is slick, very much like tobacco ads. Finally, production of e-cigarettes is essentially the Wild West of manufacturing.

Those of us in the research community understand that neither policymakers nor the general public have the luxury of waiting until the verdict is in. For all of these reasons, immediate regulation makes sense from a public health perspective.

The FDA could start by curbing e-cigarette advertising and promotion directed toward young people. Child-resistant caps could help prevent accidental poisoning of children, which has spiked as these devices proliferate. Standards for manufacturing would give us a clearer sense of what people are putting into their bodies.

And the bans on smoking tobacco cigarettes in certain places should be extended to e-cigarettes. Last month, the National Park Service banned e-cigarette use anywhere that traditional cigarettes are prohibited to protect "the health and safety of our visitors and employees,” as service Director Jonathan Jarvis explained. Moves like this will help ensure that Americans don’t embrace smoking again, whether it’s vaping or firing up a tobacco product.

How should the general public view this product? What I can say is this: If you’re a cigarette smoker, all available research shows that e-cigarettes are a safer alternative. If you don't smoke e-cigarettes or tobacco products, don’t start. Although e-cigarettes might ultimately prove to be the lesser of two evils, additional research could uncover dangers unknown today.

My ambiguity may not be satisfying in today’s in-the-minute, right-or-wrong, with-us-or-against-us world. But as long as science is guiding my research, my exploration and ultimately my decisions, I can live with that.

Cohen is director of the Institute for Global Tobacco Control and a professor at the Johns Hopkins Bloomberg School of Public Health